I started buying prescription glasses online because I’m cheap. And because I like variety. Oh, I should probably be kind and call myself a bargain-hunter or whatever, as that is also true, but really it wasn’t a matter of wanting to spend less on one pair of glasses as much as it was me wanting to have a vast selection of glasses at my disposal every day, and I could only justify that expense if I was paying markedly less per pair.

I have had a glasses fixation since before I actually needed them; as a preteen I longed for my vision to deteriorate so that I would have an excuse for glasses-wearing. I even bought a few pairs of fake glasses from mall shops like Claire’s, to pretend with, like the richly imaginative little nerd that I was.

My bad-vision dream came true in my sophomore year of high school -- I thought, for a short while, that glasses would markedly improve my abysmal Geometry grades, but no such luck -- and then I was faced with a new problem: finding glasses to suit my enormous head.

My first-ever pair were giant purple frames, like something a TV news anchor would wear. But they were all my optometrist had to fit me. I liked them, for a few months, but eventually I began catching myself in shop windows and thinking my own reflection was some middle aged-lady standing nearby. I grew to despise how much older they made me look.

Ouch.

So, like many teenagers, I got contacts. I wore contacts for a decade, in spite of the fact that they were chronically uncomfortable, probably because I did such a crap job of caring for them and would fall asleep in them all the time and have that thing happen where the contact gets stuck behind your eye and you have to fish it out. Hey, turns out I hated contacts, too. Wow, this whole crap-vision thing sure wasn’t working out to be the good time I’d imagined.

The first new pair of glasses I bought from my optometrist after swearing off contacts for good cost me a small fortune -- for me, anyway, at the time -- totaling in near $400 for frames and lenses. The frames alone were pricey, but the big-head options that weren’t giant grandpa aviators were sorely limited, so I paid it.

But I resented that cost. That was when I started looking for other possibilities.

In the intervening years, I’ve ordered from at least a dozen online prescription eyeglasses shops, with varying degrees of success. Doing so has enabled me to collect a truly embarassing assortment of the big bulky nerd glasses of my dreams. And now I’m sharing that wealth of knowledge with you.

1. The Try-On

Obviously, the biggest obstacle with ordering glasses online is not being able to try them on first. This is why, if you’ve never ordered glasses by measurement before, I recommend you go to an actual brick-and-mortar glasses shop and try some on.

I am totally going to get myself blacklisted by all optometrists everywhere for this, as your friendly neighborhood eye doctor probably makes most of her money not by giving exams, but by selling people glasses. And here I am being a jerk and suggesting you go in there and use her premises with no intention of buying anything. I’M SORRY, OPTOMETRISTS. Maybe stop jacking up the cost of lenses and coatings so much?

The point of hitting up your local glasses shop is not so much to find your One True Pair as to get a sense of what sizes and shapes fit your face best. Of course, if you find a specific pair you love, you can try to remember the make and number for it, as odds are good you can find them online for half the cost. I do not recommend going in with pen and paper to write stuff down, though, as the shop employees tend to frown upon that. Kind of like when I spend three hours browsing Barnes and Noble and ordering stuff from Amazon.com on my phone.

When you’re trying glasses on and find a pair your like, check the inside of the temples -- those are the armlike bits that hug your head. There should be a series of numbers printed there. If they’re not on the temples, they’ll be somewhere on the inner side of the glasses. These numbers represent the glasses’ size rendered in millimeters. The first number is the eye size, that is the width of the actual lens (NOT the width of the lens and the frame combined, just the lens, from seam to seam). The second number is the bridge width, which represents the bit that goes over your nose.

As you try glasses on, you’ll probably start to notice a pattern amongst the numbers of the best-fitting pairs. I prefer an eye size around 51mm myself, although I can go as low as 49mm depending on the shape and style of the glasses.

REMEMBER THESE NUMBERS. If you can’t remember them, text them to someone you love, and the shop employees will just think you’re compulsive with your phone, and not that you are collecting eyeglasses intelligence under false pretenses to assist their sworn enemies, the online eyeglasses purveyors.

Now you’re home from the eyeglasses shop. Are you wracked with guilt? I usually am, which is why I don’t actually do the above anymore, instead using my carefully cultivated knowledge of my preferred measurements and my existing glasses to make purchases.

Do you own a measuring tape? It can be a flexible sewing tape or the tough metal kind for building stuff. Even a ruler will do. Ideally it should have a metric side, but even if it doesn’t, you can still use it, you’ll just need to convert from inches. I keep probably five or six measuring tapes distributed throughout the house at all times, as I never know when I’m going to find a gorgeous vintage dress on eBay and will need to double-check my own body measurements immediately.

It’s a good idea to measure your current glasses, even if you hate them, because they’ll give you a tangible example of fit. Your head should be fairly busting with numbers by now, so start shopping.

All online glasses shops will give you measurement information for every pair of frames they carry. KNOWLEDGE IS POWER, you guys. Your meticulous glasses-shop spying and at-home measuring now begins to pay off. Using this information, you can find glasses that are extremely likely (if not guaranteed) to fit your face.

Most sites will allow you to sort by glasses shape and size, as well as by brand. Sometimes these options will be on some kind of “advanced search” page, but they will be there. I prefer to search by size first, to save myself falling in love with gorgeous glasses that won’t fit my Brobdignagian head.

Also, while many sites now offer you the chance to upload a picture of yourself to virtually “try on” various frames, keep in mind that while this can give you a rough idea of what different shapes might look like on your head, the try-on frames are rarely to scale, so they may look way bigger or smaller, depending on the picture you’re chosen, than they really are.

Sometimes a cheap purchase is a bargain, and sometimes it’s just a piece of garbage. For this reason I don’t recommend straying too far off the beaten path of well-known online eyeglasses merchants. Read reviews online. Do a Better Business Bureau search for complaints. Research is your friend.

Personal testimony: I have ordered nearly all of my Shuron and Ray-Ban frames from the Boca Raton, FL-based Best Buy Eyeglasses, and find they have pretty good customer service and reasonable prices on designer brands. I’ve also had good luck with Go-Optic. My newest source is Coastal, a site that gives you your first pair for free (seriously like the glasses are DRUGS you guys), and has a whiplash-inducingly fast order turnaround time -- generally when ordering glasses online I’m prepared to wait a few weeks for delivery, but Coastal gets them out in a matter of days.

Coastal has really great nerd glasses, too, of surprisingly high quality for their price. Also also, for every pair of glasses you buy from Coastal, they donate a pair to someone who needs them. That’s pretty awesome, right?

Yes, you will need a copy of your prescription. Some sites require your doctor’s name as well; some want the date of the prescription to make sure it’s not expired. All of this is a ruse of respectability, though. I have ordered glasses with an expired prescription many a time, from many sites, and have never had anyone actually call to verify that the prescription was still good. I just made up a more recent date for it. (I know, lying is wrong, don’t be like me.)

When you enter your prescription, check it at least three times to make sure it’s accurate. Some sites will call if a prescription looks funny, but many others will not, and it’s a major disappointment to get your new glasses only to find they don’t actually help you see.

Finally, the site you order from will need a number for your pupillary distance, or PD. This is the distance between the centers of your pupils when looking straight ahead. It’s rare that your prescription will have this information on it, which means you will probably have to acquire it via other means.

If you visit a glasses shop, they can measure your eyeballs for you, although they’ll probably charge you something for it (the one time I did this, I believe it cost me $20). This is your best bet for an accurate measurement, which is more critical the stronger your prescription is.

Alternatively, you can DIY your pupillary distance, either on your own using a mirror, or with help from a friend. There are about a million tutorials online on how to make this information happen.

5. WAIT DON’T ORDER YET.

Google for coupon codes for the website you’re ordering from. Actually, do this anytime you order anything online, although glasses sites tend to be particularly generous with them. There, I just saved you a bunch of money.

So now that I’ve talked interminably about my own tricks, here’s the part where you all testify as to your own experiences, good and bad, buying glasses online, and the websites you prefer to deal with. Let’s go.